Hectograph blanket having a wetting type bonding agent



April 29, 1941. Y Q HOUR 2fi4fi3 HECTQGRAPH BLANKET HAVING A WETTING TYPE BONDING AGENT Filed Jan. 10, 1940 Patented Apr. 29, 1941 HECTOGRAPH BLANKET HAVING A WET TING TYPE BONDING AGENT Robert C. Bour, Chicago, Ill., assignor to Ditto,

Incorporated, Chicago,

West Virginia 111., a. corporation of Application-January 10, 1940, Serial No. 313,191

2 Claims.

The invention relates to hectograph blankets and to methods of preparing the same.

Hectograph blankets generally comprise a gelatinous copy mass secured to a. flexible backing. Heretofore the backing has been secured to the copy mass by means of a bonding agent which has tanning characteristics such as, for example, linseed oil or other drying oils, or mixtures of cellulose esters and tanning agents such as alum, phenol, resorcinol, formaldehyde, and the like. Such bonding compositions have the inherent disadvantage that they cause progressive tanning of the overlying hectograph copy mass, with the result that after a period of time the hec'tograph copy mass becomes so hard thatit is not commercially usable. 4

One embodiment of the invention is a hectograph blanket in which the intermediate bonding layer is a non-tanning composition comprising a cellulose ester and a sulfonated or sulfated type wetting agent.

I have discovered that the sulfonated naphthenes are particularly effective bonding agents I when used alone or in combination with other ingredients as the intermediate bonding film or layer of a hectograph blanket. Such sulfonated naphthenes allow the production of hectograph blankets quickly and economically, and when used alone or in conjunction with other nontanning substances as the intermediate bonding film or layer, provide a hectograph blanket which remains soft and commercially usable over a long period of time.

Suitable sulfonated naphthenes include the sulfonated naphthenic acidsand alkali metal salts of naphthene sulfonic acids. Aproduct of this general type is derived from petroleum and known as mahogany soap.

The sulfonated naphthenes may be used alone, but generally are admixed with other materials, preferably non-tanning ingredients.

Other wetting agents than the sulionated naphthenes may be used, particularly in admixture with cellulose esters. are composed of a hydrocarbon chain which is hydrophobic in character, with the addition of one or more groups of strongly hydrophilic nature, which act as solubilizing groups for the compound. Wetting agents are well known and numerous synthetic oneshave been developed. While itis preferred to employ the sulfonated naphthenes. the other wetting agents may be employed, including lauryl sulfate, sulfonated castor oil, sulfated iatty acid amides, secondary alcohol sulfates, and alkyl aryl sulfonates. The

Such wetting agents a use of such wetting agents in the cellulose ester bonding layer is animprovement over the Hoskins bonding layer of Patent 2,098,662, which does not disclose wetting agents in conjunction with a non-tanning composition comprising a cellulose ester, and is also an im'provementover the Lester bonding layer of Patent 2,085,197,

ket illustrating one embodiment of my invention,

and

Fig. 2 is a sectional view of a modified form of hectograph blanket embodying my invention.

Referring to the drawing, and particularly to Fig. 1 in which'a preferred embodiment of the invention is illustrated, the reference character I is a gelatinous copy mass secured by means of a film or layer 2 comprising an acidic substance to a flexible backing consisting of a paper, cloth or other fabric base 4 coated on both sides with a relatively non-adhesive lacquer'i and 5. In the embodiment of the invention shown in Fig. 1,

' the bonding layer 2 preferably comprises one of the, usual cellulose derivative lacquerscontaining a wetting agent having a hydrophobic long chain aliphatic radical attached to. a hydrophilic S03R radical in which R. is a hydrogen or metal.

In the embodiment of the invention shown in v Fig. 2, the hectograph blanket comprises a gelatinous copy mass I secured to a paper, fabric or similar backing 4 which is impregnated with a sulfonated naphthene alone or in admixture with other ingredients, preferably of a non-tanning character. I

In the embodiment of the invention shown in both Fig. 1 and Fig. 2, the portion of the backing remote from the copy mass is covered with lacquer or similar substance illustrated by the layer 5. This outer covering is not essential, but is preferable when the hectograph blanket is to be used in the form of a roll, in order to avoid excessive adherence of the backing to the hectograph copy mass.

To more clearly set forth the practice in accordance with the invention and to more specifically point out the nature of the product and process contemplated thereby, several specific, illustrative examples are hereinafter set forth, it being understood that these examples illustrate several embodiments which have given satisfactory results and are not intended to restrict the invention thereto.

Example I.As a specific example, the fol lowing may be mentioned: Cellulose lacquer containing 37% solids is mixed with 18% of its weight of mahogany soap. The lacquer thus prepared is applied to roll backing material, allowed to dry, for example, by passing over a steam heated plate, and is then used in the manufacture of duplicating rolls, producedinlmanner well known to the art.

In addition to the mode of application described in Example I, mahogany soap maybe applied to the roll backing in the following manners:

Example Il.-Mahogany soap coated directly on the hectograph' backing.

Example IIl.-Mahogany soap in a suitable per.- centage is added to a glue, gelatin or casein mixtureof such concentration that it will harden or dry completely. Bentonite may be added.

. Parts Casein Ca(OH)2 1.8 NaOH 1.1 NaF .3 Mahogany soap 1.5 H20 20 From the above examples, it is apparent that the ingredients, proportions and procedures may be varied Within wide limits without departing from the spirit or scope of the invention. In evaluating the probable influence of such variations on the quality of bond obtained, the following may be of guidance:

Almost any carrier substance may be employed. It is not necessary, although it is preferable, to use nitrocellulose lacquers. Other films are suitable, whether the film forming material is a resin, a gum, a protein such as zein or casein, acetyl cellulose,v or inorganic colloid such as bentonitic clays or the like. Generally, the hectograph mass should not be applied until the bonding film is well dry.- Even traces of some lacquer solvents may interfere with the bonding.

Agitation or turbulence in the hectograph mass, after application to the backing, assists in forming a good bond.

, A controlling factor of the bonding qualities is the time of contact between the bacldng and the hectograph mass, before the latter congeals. Since the other factors may be varied so widely without departing from the invention, it is impossible to give any specific range for the time of contact. However, it is easy to determine the time of contact necessary for each set of conditions, by the following simple test: hectograph mass is poured onto the backing material carrying a bonding film of this invention. The backing material is kept at a temperature above the melting point of the mass for a certain time and is then allowed to cool. The next day one can readily ascertain, by trying to pull ofi the film of hectograph mass, whether or not this film adheres to the backing, or bonds. If it does not bond, the test is repeated, allowing a longer time of contact between the backing and the heotograph mass in the melted state; increasing the time of contact in melted state until bond is obtained. The conditions are then suitable for the practice of this invention.

While there have been shown and described certain embodiments of the invention, it is to be,

understood that it is capable of many modifications. Changes, therefore, may be made without departing from the spirit and scope of the invention as described in the appended claims, in which it is the intention to claim all novelty inherent in the invention as broadly as possible, in view of the prior art.

I claim:

I 1. A hectograph blanket comprising a gelatinous copy mass, a backing and an intermediate bonding layer comprising a uniform and intimate mixture of a cellulose derivative and a suifonated naphthene.

2. The method of preparing a hectograph blanket which comprises apply-ing to a backing a coating composition comprising an intimate dispersion of a sulfonated naph-thene and a under substance in a volatile liquid, evaporating the liquid .to produce a dried bonding layer, and applying a layer of a gelatinous copy mass to the dried bonding layer.

ROBERT c. BOUR. v 

